INFO: I have a Sonicwall firewall/router and I cannot sync my iPhone!
Some models of wireless router/firewall devices from Sonicwall will block Apple's Bonjour service, and thus block eWallet sync from working.
So far, we have identified the TZ-190 and TZ-150 as devices that block Bonjour. As far as we know, the router cannot be configured to allow Bonjour; it's inherent to the design of the router.
If you have one of these routers, you will need to use an ad-hoc wireless network to sync with your iPhone or iPod Touch. An ad-hoc network requires that you have a wireless network adapter connected to your computer (built-in, as a PC Card or Express card, or via USB.)